While various problems associated with the inefficient use of network resources plague a wide variety of communication networks, they have more serious consequences in networks which rely on radio frequency (RF) communication links.
Space-based and terrestrial-based communication systems must share a limited frequency spectrum. The need to constantly increase the capacity of space-based and terrestrial-based communications systems has resulted in the continuing evolution of antenna technology. Antennas can provide multiple beams using spatial and/or polarization isolation techniques. Advances are still required to provide enhanced performance with respect to antennas generating adaptive antenna beam patterns. Adaptive antenna patterns have been generated using a variety of active and passive phased arrays.
Communication systems have used phased array antennas to communicate with multiple users through multiple antenna beams. Typically, efficient bandwidth modulation techniques are combined with multiple access techniques, and frequency separation methods are employed to increase the number of users.
Increased efficiency can be obtained by improving the antenna being used for an RF communication link. Furthermore, there is no known low cost phased array topology practical at microwave and/or millimeter wave frequencies for forming simultaneous multiple beams from a single aperture.
Accordingly, a need exists to form simultaneous independently steerable multiple beams in a low cost phased array antenna that is practical at microwave and/or millimeter wave frequencies.
In particular, there is a significant need for apparatus and methods for providing multiple beams from a single antenna which can be independently steered over a wide angle field of view.